The answer is that the Cloud Build service account lacks the storage.objectAdmin role on the Container Registry bucket. This is the most likely cause because Kaniko, when used as a builder in Cloud Build, relies on the service account’s metadata credentials to authenticate with Google Container Registry. Without the storage.objectAdmin role—which grants write and delete permissions on bucket objects—Kaniko cannot push the built image, resulting in the “failed to get credentials” error. On the Google Professional Cloud DevOps Engineer exam, this scenario tests your understanding of how Cloud Build service accounts interact with GCP IAM roles, often appearing as a trap where candidates mistakenly blame network issues or misconfigured Dockerfiles. A common memory tip is to remember that Kaniko pushes images like a storage operation: if you can pull but not push, you need objectAdmin or objectCreator, not just objectViewer.
PCDOE Building and implementing CI/CD pipelines Practice Question
This PCDOE practice question tests your understanding of building and implementing ci/cd pipelines. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A team uses Cloud Build with a Kaniko builder to containerize their application. The build fails with the error: 'failed to push to destination: failed to get credentials: failed to get credential from metadata service: failed to fetch metadata...' What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Cloud Build service account does not have the storage.objectAdmin role on the Container Registry bucket.
The error indicates that Kaniko cannot authenticate to push the built image to Container Registry. Kaniko uses the Cloud Build service account's credentials to authenticate with the registry. By default, the Cloud Build service account has the storage.objectViewer role on the Container Registry bucket, which allows pulling images but not pushing. To push, the service account needs the storage.objectAdmin or storage.objectCreator role on the bucket. Option D correctly identifies this missing permission as the most likely cause.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Kaniko requires a running Docker daemon in the build step.
Why it's wrong here
Kaniko is daemonless; it does not need Docker.
✗
The base image specified in the Dockerfile is not accessible from the build environment.
Why it's wrong here
Pull errors are different; the error indicates push failure.
✗
The Dockerfile has an invalid instruction causing Kaniko to fail.
Why it's wrong here
Syntax errors produce different error messages.
✓
The Cloud Build service account does not have the storage.objectAdmin role on the Container Registry bucket.
Why this is correct
Missing push permissions cause credential failures.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that Kaniko requires a Docker daemon (Option A), but the real issue is almost always a missing IAM permission on the target registry bucket.
Detailed technical explanation
How to think about this question
Kaniko extracts the base image layers, executes the Dockerfile commands in a snapshot-based sandbox, and then pushes the final image layers to a registry. The push step uses the default application default credentials (ADC) from the Cloud Build environment, which are tied to the Cloud Build service account (typically <PROJECT_NUMBER>@cloudbuild.gserviceaccount.com). The Container Registry bucket is a Google Cloud Storage bucket (gs://artifacts.<PROJECT_ID>.appspot.com), and the service account must have the storage.objects.create permission (provided by roles/storage.objectAdmin or roles/storage.objectCreator) on that bucket to upload layers and the manifest.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Building and implementing CI/CD pipelines — This question tests Building and implementing CI/CD pipelines — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The Cloud Build service account does not have the storage.objectAdmin role on the Container Registry bucket. — The error indicates that Kaniko cannot authenticate to push the built image to Container Registry. Kaniko uses the Cloud Build service account's credentials to authenticate with the registry. By default, the Cloud Build service account has the storage.objectViewer role on the Container Registry bucket, which allows pulling images but not pushing. To push, the service account needs the storage.objectAdmin or storage.objectCreator role on the bucket. Option D correctly identifies this missing permission as the most likely cause.
What should I do if I get this PCDOE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This PCDOE practice question is part of Courseiva's free Google Cloud certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCDOE exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.